These guys may be an option - obviously not an EBay retailer.
https://powerwindowrepair.com/
They list the NSX as one of the cars that they offer repairs for; but, they may just list every model of every manufacturer. There was a post from a Prime user talking about trying their repair service; but, there was no follow-up so maybe the results were not satisfactory?
There is also this vendor:
http://windowmotorworld.net/
At least one Prime user tried these guys in the past and reported satisfactory results.
If you need a replacement motor, I believe that North American Honda Accords of around 1993 vintage use the same motor. You do have to be careful in picking the correct regulator because the Accord used both a scissors style regulator and a cable style regulator and I believe that it is the cable style regulator that has the correct motor. Note that this is just the electric motor, not the complete cable drive mechanism. Some of the cable drive parts /drum might be interchangeable. There were some suggestions that some of the Accord regulators were a complete direct replacement for the NSX regulator. Visual inspection of the 1993 Accord cable style regulator shows that it is definitely not a direct replacement for the NSX regulator - the cable exits on the drive unit are significantly different.
I had all this stuff bookmarked in case my Hugo repair did not work out. Fortunately the Hugo repair did the trick for me.